✨🎩 postinstaller

Publish dev-friendly ❤️ zero-configuration packages.

Motivation

Adding new packages to a project often requires manual configuration of package.json, which can be tedious, error prone and frustrating.

Wouldn’t life be great if we could just add a package and be done?

Postinstaller does exctly that. It’s a tool for package authors that configures package.json automatically when their package gets installed - and also cleans up again if the package gets removed.

Features

• Automatic configuration.
• Automatic cleanup.
• Easy to set up.

Use Cases

• Zero-Config plugins. Automatically add your plugin to the right package.json key.

For Package Developers

Setting a value

Postinstaller makes it very easy to set values in a JSON config file. Here’s an example:

Example

{
  "postinstaller": {
    "scripts.hello": "echo 'hello, world!'"
  }
}

Postinstaller uses dot notation to address values. In the example above, the recipe will set hello in the scripts section to echo 'hello, world!'.

Result

{
  "scripts": {
    "hello": "echo 'hello, world!'"
  }
}

Postinstaller never silenty overwrites values.

Operations

• Set. Set a value.
• Insert. Insert a value into an array.
• If has. Check if a file has a certain key.

Set

Example: standard-version

{
  "postinstaller": {
    "scripts.release": "standard-version"
  }
}

If has ✓

Example: ava and setup-browser-env

If ava is installed, add setup-browser-env to the list of required modules

{
  "postinstaller": {
    "devDependencies.ava?": {
      "ava.require[]": "setup-browser-env"
    }
  }
}

Example: husky and commitlint

if devDependencies.husky AND devDependencies.@commitlint/cli? exist, add husky.hooks.commit-msg:

{
  "postinstaller": {
    "devDependencies.husky?": {
      "devDependencies.@commitlint/cli?": {
        "husky.hooks.commit-msg": "commitlint -E HUSKY_GIT_PARAMS"
      }
    }
  }
}

Backlog

Concatenate Shell Commands

Example: postinstaller

• &&before
• after&&

{
  "postinstaller": {
    "&& scripts.postinstaller": "postinstaller install",
    "&& scripts.preuninstall": "postinstaller uninstall",
  }
}

Configure other files

Example: configure another file

{
  "postinstaller": {
    "file babel.json": {
      :
    }
  }
}

Regex Replace

Example: configure ava (Regex Replace)

{
  "postinstaller": {
    "devDependencies.nyc?": {
      "scripts.test": "/ava|mocha/nyc $0"
    }
  }
}

Shared Postinstaller Scripts

Some packages unfold their full power when they are used together with other packages: ava and nyc, commitlint and husky are good examples for this.

• Create a package postinstaller-abc-def.
• Publish to npm.
• Add as a dependency to all packages.

Guidelines

• Never overwrite or delete values. Append and remove smartly instead.